Citation index including signals

ABSTRACT

A document, which may be referred to as a “citing document,” may include citations to one or more cited documents. An index of such documents may be referred to as a citation index or citator. A citation may be preceded in a citing document by introductory text, which may be called a signal, and one or more entries in a citation index may indicate which signal, if any, introduced a recorded citation. Computerized systems and methods for causing such display are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.11/947,410, filed Nov. 29, 2007, now U.S. Pat. No. 8,332,384, and titled“Creation and Maintenance of a Body of Knowledge Using NormalizedTerminology.” This application is also related to pending U.S. patentapplication Ser. No. 11/412,315, filed Apr. 26, 2006, and titled “Systemand Method for Topical Document Searching,” which is incorporated hereinby reference.

COPYRIGHT NOTICE

A portion of the disclosure of this patent document contains materialthat is subject to copyright protection. The copyright owner has noobjection to the facsimile reproduction by anyone of the patent documentor the patent disclosure as it appears in the Patent and TrademarkOffice patent files or records, but otherwise reserves all copyrightswhatsoever.

BACKGROUND

The volume of readily available information related to any fieldcontinues to grow, and the rate of growth is accelerating. Thecapacities to organize and index this information have not kept pace,however. It has consequently become more likely that informationprecisely responsive to any need exists, while it has become less likelythat anyone needing that responsive information will be able to find it.

The legal field has long and acute experience with these problems.Increased resort to the courts to address questions of public policy hashad the consequence of increasing the volume of precedent that must beassimilated. The growth of the regulatory state has meant an increase inthe number of regulations and administrative rulings. And theconsequences of overlooking any applicable legal authority can be dire.

Before the coming of the personal computer, legal practitionersdeveloped elaborate systems for organizing, indexing, and retrievinginformation. Among the elements of such systems are headnotes, which areannotations that state the major points of a judicial opinion; digests,which organize by subject headnotes collected from many opinions; andcitators, which index the citations between documents. Headnotes,digests, and citators remain in wide use.

As in other fields, legal practitioners have applied computers andcomputer networks to the problems in managing information. Databases oflegal information, containing, e.g., opinions, headnotes, digests, andother secondary material are available through networks of computers.

BRIEF SUMMARY OF THE INVENTION

The invention relates to the organization, maintenance, and use of abody of knowledge and computer systems and methods applicable thereto.More specifically, it relates to the identification of principles thatmake up the body of knowledge, creation of standard expressions of theprinciples, and arrangement of the expressions within a framework withinwhich information, in the form, e.g., of documents, can be associatedwith the principles that it relates to. It further relates to systemsand methods for classifying, storing, searching for, retrieving, andpresenting information organized within that framework.

According to an embodiment of the invention, an outline can be provided,e.g., for a field of knowledge, study, and/or endeavor. The outline maybe associated with and/or accompanied by a collection of documentsrelated to the outlined field. The outline may take the form, forexample, of a hierarchical list of topics (a “topic hierarchy”), whereinone or more topics may each comprise one or more respective subtopics,which may in turn comprise further subtopics, etc.

In connection with an embodiment of the invention, documents within thecollection may refer to (e.g., cite) and/or otherwise be associated withothers within the collection. As a special case of the foregoing, somedocuments may be created, e.g., to describe and/or survey one or moretopics and/or subtopics within the topic hierarchy and to do so withreference to one or more other documents within the collection. Thesereferences and/or other associations may be used, e.g., to definesub-collections within the larger collection, and searching may besupported within such sub-collections. Such sub-collections may also beassociated with a topic and/or subtopic through use of a document knownto be associated with the topic and/or subtopic as the basis forbuilding one such collection.

Additionally, in an embodiment of the invention, associations betweendocuments may be, e.g., indexed to create a citator. Besides recordingthe simple association between one document and another, however, acitator according to an embodiment of the invention may record the formand/or substance of the association, and, according to a furtherembodiment of the invention, some or all of this information may beexpressed in standard terms, which may differ from the actual terms usedin any or all of the documents. Such standard terms, or “standardexpressions” may in an embodiment of the invention be collected andorganized, e.g., according to the topic hierarchy, and, in an embodimentof the invention, such organization is used to create a synopsis of theentire field.

Although the invention is of general applicability, particular attentionis given herein to the application of the invention to legalinformation.

Thus, according to an embodiment of the invention, a method is providedof providing a synopsis of a body of knowledge. The method comprisesstoring within at least one electronic database a representation of atopic hierarchy that comprises a plurality of topics related to the bodyof knowledge, at least one topic comprising one or more subtopics, andat least one subtopic further comprising one or more subtopics. Themethod also comprises, for each of a plurality of documents, at leastone of which is a citing document that includes at least one citation toat least one of the plurality of documents, finding at least onestatement within the document that expresses a principle related to thebody of knowledge, and, for each of the principles identified in any oneor more of the documents, creating a standard expression of theprinciple and storing the created expression within the at least oneelectronic database in relation to at least one of the subtopics and inrelation to each of the documents in which the identified principle wasexpressed.

According to an embodiment of the invention, each of the standardexpressions expresses a rule of law.

According to another embodiment of the invention, the method comprisesfinding, within a citing document, a citation to one other document ofthe plurality of documents and a statement, associated with thecitation, that is substantially equivalent to one of the standardexpressions; and storing the citing document in relation to the otherdocument and in relation to the subtopic that is related to the standardexpression. In an embodiment of the invention, the method comprisesproviding an indication that the citing document includes the citationto the one other document and an identification of the standardexpression.

According to an embodiment of the invention, a method is provided ofproviding a citation index. The method comprises finding within a firstdocument a first expression of a principle, storing within the at leastone database a first association between the first document and astandard expression of the principle, finding within a second document asecond expression of the principle and a citation to the first document,the citation being associated with the second expression of theprinciple, storing within the at least one database a second associationbetween the second document and the standard expression of the principleand a third association between the second document and the firstdocument, and providing an indication that the second document includesthe citation to the first document and an identification of the standardexpression of the principle.

In an embodiment of the invention, the method comprises storing withinthe at least one database, in association with the standard expressionof the principle, information indicating a treatment within the seconddocument of the first expression of the principle; and providing anindication of the treatment and an identification of the first document.In an alternative embodiment of the invention, the method comprisesstoring within the at least one database a fourth association betweenthe standard expression of the principle and a subtopic within a topichierarchy that comprises a plurality of topics related to a body ofknowledge, at least one topic comprising one or more subtopics, and atleast one subtopic further comprising one or more subtopics.

In connection with the foregoing embodiments of the invention, theexpressed principle may be a rule of law. In connection with theforegoing embodiments of the invention, one or more of the documents maybe judicial opinions.

According to an embodiment of the invention, a system is provided forproviding a synopsis of a body of knowledge. The system comprises aprogrammable processor, an input device that provides input to thesystem, a database, and a memory. The memory stores instructions that,when executed by the processor, cause the system to carry out a methodthat comprises storing within the at least one database a representationof a topic hierarchy that comprises a plurality of topics related to thebody of knowledge, at least one topic comprising one or more subtopics,and at least one subtopic further comprising one or more subtopics; foreach of a plurality of documents, receiving first input through theinput device designating at least one statement within the document thatexpresses a principle related to the body of knowledge; and for each ofthe principles designated in any one or more of the documents, receivingsecond input, through the input device, that indicates a standardexpression of the principle and, in response to the second input,storing that expression within the at least one database in relation toat least one of the subtopics and in relation to each of the documentsin which the principle was expressed.

According to an embodiment of the invention, each standard expressionexpresses a rule of law. According to an alternative embodiment of theinvention, the method comprises receiving third input through the inputdevice, designating within a citing document a citation to one of thedocuments, a statement that is substantially equivalent to one of thestored standard expressions, and an association between the citation andthe statement; and storing the citing document in the at least onedatabase in relation to the cited document and in relation to thesubtopic that is related to the standard expression.

According to an embodiment of the invention, the method comprisesproviding an indication that the second document includes the citationto the first document and an identification of the standard expression.

According to an embodiment of the invention, a system is provided forproviding a citation index. The system comprises a programmableprocessor, an input device that provides input to the system, adatabase, and a memory. The memory stores instructions that, whenexecuted by the processor, cause the system to carry out a method thatcomprises accepting first input through the input device designatingwithin a first document a first expression of a principle; storingwithin the at least one database a standard expression of the principle;storing within the at least one database a first association between thefirst document and the standard expression of the principle; acceptinginput through the input device designating within a second document asecond expression of the principle and a citation to the first document,the citation being associated with the second expression of theprinciple; storing within the at least one database a second associationbetween the second document and the standard expression of the principleand a third association between the second document and the firstdocument; and providing an indication that the second document includesthe citation to the first document and an identification of the standardexpression of the principle.

According to an embodiment of the invention, the method comprisesstoring within the at least one database, in association with thestandard expression of the principle, information indicating a treatmentwithin the second document of the first expression of the principle; andproviding an indication of the treatment and an identification of thefirst document. According to an alternative embodiment of the invention,the method comprises storing within the at least one database a fourthassociation between the standard expression of the principle and asubtopic within a topic hierarchy that comprises a plurality of topicsrelated to a body of knowledge, at least one topic comprising one ormore subtopics, and at least one subtopic further comprising one or moresubtopics.

In connection with the foregoing embodiments of the invention, theexpressed principle may be a rule of law. In connection with theforegoing embodiments of the invention, one or more of the documents maybe judicial opinions.

According to an embodiment of the invention, a computer-readable storagemedium is provided that is encoded with a data structure. The datastructure comprises a representation of a topic hierarchy that comprisesa plurality of topics related to a body of knowledge, at least one topiccomprising one or more subtopics, and at least one subtopic furthercomprising one or more subtopics; a plurality of standard expressions,each expressing a principle related to the body of knowledge; for eachof the standard expressions, at least one association between therespective standard expression and one of the subtopics; and for each ofthe standard expressions, at least one association between therespective standard expression and a document that includes subjectmatter associated with the body of knowledge, the document including atleast one statement having a meaning that is substantially equivalent tothe meaning of the respective standard expression.

According to an embodiment of the invention, each of the standardexpressions expresses a rule of law. According to an alternativeembodiment of the invention, the data structure comprises a plurality ofassociations among a plurality of documents, each association itselfbeing associated with at least one of the standard expressions.

In an embodiment of the invention, a method is provided of displaying anentry in a citation index. The entry corresponds to at least onecitation in a citing document that comprises text, and at least one ofthe citations identifies a cited document and is introduced in the textof the citing document by a signal. The method comprises retrieving froma computer-readable storage medium first information that identifies theciting document and second information that identifies the signal in theciting document that introduced the citation to the cited document andcausing an electronic display device to display the entry, the entrybeing based on the first information and the second information andcomprising identification of the citing document and identification ofthe signal. According to an embodiment of the invention, the entryincludes the signal.

Embodiments of the invention also include systems, e.g., for providingdisplays and/or carrying out the methods described above. Such a systemmay comprise a programmable processor, an input device that providesinput to the system, a database, and a memory. The memory may storeinstructions that, when carried out by the processor, cause the systemto carry out a method such as described above.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is illustrated in the figures of the accompanyingdrawings, which are meant to be exemplary and not limiting, and in whichlike references are intended to refer to like or corresponding things.

FIG. 1 illustrates a presentation of the contents and layout of one kindof citator according to the prior art.

FIG. 2 is a block diagram of a programmable digital computer accordingto the prior art.

FIG. 3 is a block diagram depicting internetworked computer systemsaccording to the prior art.

FIG. 4 depicts a display of direct history within an electronic citatorsuch as may be provided in connection with an embodiment of theinvention.

FIG. 5 depicts a display of indirect history within an electroniccitator such as may be provided in connection with an embodiment of theinvention.

FIG. 6 depicts a display of an item of indirect history from the displaydepicted in FIG. 5.

FIG. 7 depicts an alternate display of indirect history within anelectronic citator such as may be provided in connection with anembodiment of the invention.

FIGS. 8 and 9 are flowcharts representing analysis of a new document forinclusion in a citator according to an embodiment of the invention.

FIG. 10 depicts a presentation of Points of Law for a specific subtopicaccording to an embodiment of the invention.

FIG. 11 depicts an alternative presentation of the specific Points ofLaw depicted in FIG. 10 according to an embodiment of the invention.

FIGS. 12-15 depict displays such as may be presented in the course ofusing a Legal Topic Hierarchy according to an embodiment of theinvention.

FIGS. 16-18 depict displays such as may be presented in the course ofsearching within a Legal Topic Hierarchy according to an embodiment ofthe invention.

FIG. 19 depicts a discussion Law Note according to an embodiment of theinvention.

FIG. 20 depicts a law list Law Note according to an embodiment of theinvention.

FIG. 21 depicts a directory Law Note according to an embodiment of theinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the invention provide systems and methods for assistingand enhancing research within bodies of knowledge. For example, one suchbody of knowledge is the law applicable in one or more jurisdictions,which may subsume, e.g., statutes, case law (e.g., judicial opinions),administrative regulations and orders, legislative history, commentary,treatises, journals, etc. The invention is illustrated herein throughdiscussion of embodiments related to such legal information, andespecially to opinions rendered by governmental adjudicative entities(e.g., courts and administrative agencies, among others), but this isexemplary, not limiting.

Published judicial opinions in the United States commonly begin with oneor more numbered headnotes, each headnote restating a significantprinciple from the opinion that it annotates. Each headnote tends to beshort, commonly only a single sentence. With rare exceptions, a headnoteis added by a reporter or publisher, as a convenience for the reader,and thus lacks precedential value. As editorial additions to an opinion,moreover, headnotes may be protected by copyright.

For example, an opinion from a court disposing of a motion for summaryjudgment under the Federal Rules of Civil Procedure might recite thelegal standard for granting such a motion. Rule 56(c) of the FederalRules says when summary judgment is proper:

-   -   The judgment sought should be rendered if the pleadings, the        discovery and disclosure materials on file, and any affidavits        show that there is no genuine issue as to any material fact and        that the movant is entitled to judgment as a matter of law.

To prepare the headnotes for an opinion, an editor typically reads theopinion, identifies the principles it states, and then writes a headnotefor each principle. A summary judgment opinion might include a headnotesuch as the following:

-   -   [1] Summary judgment should be rendered if the pleadings, the        discovery and disclosure materials on file, and any affidavits        show that there is no genuine issue as to any material fact and        that the movant is entitled to judgment as a matter of law.

Headnotes are typically prepared anew for each opinion, however, andoften follow the language used by the opinion's author. Thus, a headnoteexpressing the same principle might in connection with another opinionread:

-   -   [1] Summary judgment should not be rendered unless the        pleadings, the discovery and disclosure materials on file, and        any affidavits show that there is no genuine issue as to any        material fact and that the movant is entitled to judgment as a        matter of law.

Still another headnote might read:

-   -   [1] Summary judgment is proper if there is no genuine issue as        to any material fact.

Headnotes may be collected in a reference called a digest. Commondigests include headnotes, from one or more jurisdictions, publishedwithin a specified time. The headnotes may be organized or indexedaccording to one or more attributes, such as legal subject matter,jurisdiction, and date, and each headnote is commonly accompanied by acitation allowing the reader to locate the opinion from which theheadnote was taken. But because of the way headnotes are created, asdiscussed above, the sections of a digest that deal with basicprinciples of law commonly include page after page of substantiallyidentical headnotes.

It is in some circumstances desirable to know if a document has beencited by other documents. In law, for example, a judicial opinion mayappear on its face to be mandatory or persuasive authority for aparticular legal principle. The effect of the decision represented bythe opinion, however, may be diminished, or even negated entirely, bysubsequent decisions. Conversely, a particular opinion may be judged tohave special import if other opinions cite it often and favorably.

In law, an index of citing documents may be known as a “citator.” FIG. 1depicts an entry 100 in a representation of a citator according to theprior art. The entry comprises a caption 110, which in the depictedcitator is in the form of a citation to the indexed opinion. Asdepicted, beneath the caption is a list 112 of opinions and/or otherdocuments that cite the indexed opinion.

The list 112 comprises one or more items 114, each of which includesinformation in up to three columns. For any entry, the leftmost column116 may hold a description of how the citing document treated theindexed opinion. Possible treatments resulting from further proceedingsin the same or related cases (sometimes called the “direct history”)include, for example, denial of discretionary review, affirmance, andreversal by an appellate court. Possible treatments in other,independent cases (sometimes called the “indirect history”) include, forexample, following the reasoning or rule of the indexed opinion,discussing the indexed opinion, criticizing it, declining to follow it,and overruling the previous decision. It is common for many items in thelist 112 to omit treatment information.

The center column 118 holds an abbreviated citation to the citingdocument.

The rightmost column 120 may indicate the principle or principles forwhich the citing document referred to the indexed opinion. In thedepicted citator, this indication takes the form of one or more numbers,where each number corresponds to one of the headnotes written for theopinion by the reporter of decisions. One or more list items 112 mayhave multiple headnote numbers, and one or more of them may have noheadnote numbers at all.

The invention disclosed herein may be practiced using programmabledigital computers. FIG. 2 is a block diagram of a representative priorart computer. The computer system 140 includes at least one processor145, such as an Intel Core™ 2 microprocessor or a Freescale™ PowerPC™microprocessor, coupled to a communications channel 147. The computersystem 140 further includes an input device 149 such as, e.g., akeyboard or mouse, an output device 151 such as, e.g., a CRT or LCDdisplay, a communications interface 153, a data storage device 155 suchas a magnetic disk or an optical disk, and memory 157 such asRandom-Access Memory (RAM), each coupled to the communications channel147. The communications interface 153 may be coupled to a network suchas the Internet.

One skilled in the art will recognize that, although the data storagedevice 155 and memory 157 are depicted as different units, the datastorage device 155 and memory 157 can be parts of the same unit orunits, and that the functions of one can be shared in whole or in partby the other, e.g., as RAM disks, virtual memory, etc. It will also beappreciated that any particular computer may have multiple components ofa given type, e.g., processors 145, input devices 149, communicationsinterfaces 153, etc.

The data storage device 155 and/or memory 157 may store an operatingsystem 160 such as Microsoft Windows XP® or Vista™, Linux®, Mac OS®, orUnix®. Other programs 162 may be stored instead of or in addition to theoperating system. It will be appreciated that a computer system may alsobe implemented on platforms and operating systems other than thosementioned. Any operating system 160 or other program 162, or any part ofeither, may be written using one or more programming languages such as,e.g., Java®, C, C++, C#, Visual Basic®, VB.NET®, Perl, Ruby, Python, orother programming languages, possibly using object oriented designand/or coding techniques.

One skilled in the art will recognize that the computer system 140 mayalso include additional components and/or systems, such as networkconnections, additional memory, additional processors, networkinterfaces, input/output busses, for example. One skilled in the artwill also recognize that the programs and data may be received by andstored in the system in alternative ways. For example, acomputer-readable storage medium (CRSM) reader 164, such as, e.g., amagnetic disk drive, magneto-optical drive, optical disk drive, or flashdrive, may be coupled to the communications bus 147 for reading from acomputer-readable storage medium (CRSM) 166 such as, e.g., a magneticdisk, a magneto-optical disk, an optical disk, or flash RAM.Accordingly, the computer system 140 may receive programs and/or datavia the CRSM reader 164. Further, it will be appreciated that the term“memory” herein is intended to include various types of suitable datastorage media, whether permanent or temporary, including among otherthings the data storage device 155, the memory 157, and the CSRM 166.

Two or more computer systems 140 may be connected, e.g., in one or morenetworks, via, e.g., their respective communications interfaces 155and/or network interfaces (not depicted). FIG. 3 is a block diagram ofrepresentative prior art interconnected networks 180, such as may beuseful in connection with embodiments of the invention.

A network 182 may, for example, connect one or more workstations 184with each other and with other computer systems, such as file servers186 or mail servers 188. The connection may be achieved tangibly, e.g.,via Ethernet® or optical cables, or wirelessly, e.g., through use ofmodulated microwave signals according to the IEEE 802.11 family ofstandards. A computer system that participates in the network may senddata to another computer system in the network via the networkconnection.

One use of a network 180 is to enable a computer system to provideservices to other computer systems, consume services provided by othercomputer systems, or both. For example, a file server 186 may providecommon storage of files for one or more of the workstations 190 on anetwork 182. A workstation 190 sends data including a request for a fileto the file server 186 via the network 182 and the file server 186 mayrespond by sending the data from the file back to the requestingworkstation 190.

As will be recognized by those skilled in the relevant art, the terms“workstation,” “client,” and “server” are used herein to describe acomputer's function in a particular context. A workstation may, forexample, be a computer that one or more users work with directly, e.g.,through a keyboard and monitor directly coupled to the computer system.A computer system that requests a service through a network is oftenreferred to as a client, and a computer system that provides a serviceis often referred to as a server. But any particular workstation may beindistinguishable in its hardware, configuration, operating system,and/or other software from a client, server, or both.

Further, a computer system may simultaneously act as a workstation, aserver, and/or a client. For example, as depicted in FIG. 3, aworkstation 192 is connected to a printer 194. That workstation 192 mayallow users of other workstations on the network 182 to use the printer194, thereby acting as a print server. At the same time, however, a usermay be working at the workstation 192 on a document that is stored onthe file server 186.

A network 182 may be connected to one or more other networks 180, e.g.,via a router 196. A router 196 may also act as a firewall, monitoringand/or restricting the flow of data to and/or from a network 180 asconfigured to protect the network. A firewall may alternatively be aseparate device (not pictured) from the router 196

A network of networks 180 may be referred to as an internet. The term“the Internet” 200 refers to the worldwide network of interconnected,packet-switched data networks that uses the Internet Protocol (IP) toroute and transfer data. A client and server on different networks maycommunicate via the Internet 200. For example, a workstation 190 mayrequest a World Wide Web document from a Web Server 202. The Web Server202 may process the request and pass it to, e.g., an Application Server204. The Application Server 204 may then conduct further processing,which may include, for example, sending data to and/or receiving datafrom one or more other data sources. Such a data source may include,e.g., other servers on the same network 206 or a different one and/or aDatabase Management System (“DBMS”) 208.

Citator

FIG. 4 depicts an exemplary display 230 of direct history that anelectronic legal citator may present in connection with an embodiment ofthe invention. The display comprises a citation 232 to the 1908 opinion(the “indexed opinion”) of the Supreme Judicial Court of Massachusettsin the matter of Maynard v. Royal Westchester Corset Co., in one formthat is commonly used to identify legal opinions. The display 230 alsocomprises a summary 234 of the decision of the court that issued theindexed opinion.

The display 230 comprises an area 240 for presentation of the directhistory. Within this area 240, a citation 242 to the indexed opinion maybe presented along with one or more citations to other decisions in thecase, thereby showing the context in which the opinion issued. One ormore entries in the direct history may comprise an explanatory phrasethat indicates the relationship between the associated entry and one ormore other entries in the direct history.

Some decisions and opinions are unreported or otherwise unavailable.When an entry refers to such an unavailable resource, a placeholder 246(e.g., “Unpublished Opinion”) may indicate that a relationship involvessuch a resource.

The display 230 includes tabs to indicate the availability of multiplekinds of information. The tab 250 labeled “Direct History” includes textin boldface, which indicates that the direct history of the indexedopinion is currently displayed. The other tab 252, labeled “CitationAnalysis,” is a hyperlink to a display 260 of indirect history, such asFIG. 5 depicts.

The citator depicted in FIG. 5 comprises a list 265 of documents thatcite the indexed opinion. A citation 267 to this opinion appears at thetop of the display 260 in one form that is commonly used to identifyjudicial opinions. As depicted, the citation 267 is a hyperlink to thetext of the indexed opinion (not depicted). This example also includes abrief statement 269 of the result that the court reached in the indexedopinion, presented just below the citation 267.

As depicted in FIG. 5, the citator presents a list 265 of all opinions(the “citing opinions”) that are known to have cited the indexedopinion, and FIG. 6 depicts a single entry 275 from that list. The entry275 includes a citation 277 to the citing case in one form commonly usedto identify judicial opinions. As depicted, the citation 277 is ahyperlink to the text of the citing opinion (not depicted). Adjacent tothe citation 277 is a symbol 279 (e.g., “+” or “×”) that may indicatethe continued significance of the citing opinion in view of subsequentevents. An alternative implementation of a citator may omit such anindication entirely or provide other indicia (e.g., annotation with oneor more characters or words, color-coding, highlighting, and/orselection of a typeface and/or one or more attributes thereof for someor all of the entry) of the significance of a citing opinion in additionto or instead of one or more symbols as depicted in FIGS. 5 and 6.

As depicted in FIG. 6, an entry 275 includes a symbol 281 that indicatesthe citing opinion's treatment of the indexed opinion. The exemplarycitator (FIG. 5) uses five symbols 281, and a key 283 to the meanings ofthe symbols is included in the display 260. For example, the plus sign(“+”) in a green square 281, depicted in FIG. 6, indicates positivetreatment, e.g., that the citing opinion explicitly indicated approvalof indexed opinion or did so implicitly by accepting the authority orguidance of the indexed opinion.

The depicted entry 275 also describes the form of the reference withinthe citing opinion. For example, the depicted entry includes thedescription “CITED (See also)” 285. An entry 275 in a citator mayvariously comprise descriptions that indicate, e.g., that a citingopinion also discussed the indexed opinion or quoted a portion of it. Asdepicted in FIG. 6, the description 285 also indicates that the citationin the citing opinion was introduced by the words “See also” 287 whichmay be considered an example of a “signal.”

Returning to FIG. 5, the display 260 includes a summary 290 of theciting opinions' treatment of the indexed opinion. The depicted exampleindicates that 97 opinions cited the cited the indexed opinion. Of theciting opinions, as indicated in the analysis summary 283, 96 treatedthe indexed opinion positively, and 1 treated the indexed opinion in away that suggests caution in relying on the indexed opinion.

As depicted in FIG. 5, the entries are sorted by the dates of the citingopinions that they represent, with the most recently issued opinionslisted first. Other sort keys may be used in an embodiment of theinvention (not pictured) instead of or in addition to the date of theopinion, including, for example, one or more of the jurisdiction (e.g.,federal court or one of the state courts), the court level (e.g., trialor appellate), and the opinion type (e.g., majority, per curiam,concurring, or dissenting), among other possibilities. Any one or morecriteria, including for example any one or more of the preceding sortcriteria, may also be used in an embodiment of the invention (notpictured) to break the list of citations into groups.

The display 260 (FIG. 5) includes a hyperlink 292 that leads to themodified display 300 depicted in FIG. 7. As depicted therein, each entry275 in the citator is accompanied by an excerpt 302 from the citingopinion that includes the citation 304, providing context. A hyperlink306 leads, e.g., back to the display 260 depicted in FIG. 5.

As depicted in FIGS. 5 and 7, either all citations are accompanied byexcerpts, or none of them are. In an embodiment of the invention, one ormore user interface components (not pictured) may be provided that allowexcerpts to be displayed and/or hidden in connection with citationsindividually and/or in groups.

As discussed above, a citator may identify the aspect of the indexedopinion that the citing opinion refers to. For example, a citator mayidentify the page or pages of the indexed opinion that the citingopinion discusses. An alternative citator may refer to one or morepoints discussed in the indexed opinion, e.g., by including with theentry for each citing opinion an indication of the point or pointsdiscussed, such as a headnote number. In practice, these approaches canbe expected to have similar results, and a particular citator may useeither approach or a combination of the two.

In an embodiment of the invention, an alternative to headnotes is used.In such an embodiment, a plurality of opinions are selected that arejudged respectively to express certain principles of law in arepresentative manner. The selection criterion or criteria may varydepending on the embodiment of the invention, but may include one ormore of, for example, the quality of the writing, the degree to whichthe phrasing has been quoted elsewhere, and the importance and/orauthority of the court.

According to this embodiment of the invention, such expressions may thenbe adopted, as-is or edited, as a standard by a publisher of a citator,who may then describe the propositions expressed in any opinion in termsof the selected standard of expressions. Following such an approach, acitator may then include in an entry for a citing opinion, again interms of one or more of the standard of expressions, an indication ofthe citing opinion's treatment of one or more legal principles stated inthe indexed opinion.

A selected standard expression can be taken as setting forth a Point ofLaw. Once a standard expression has been chosen, other opinions'statements on that point may be expressed in terms of the standardexpression, e.g., by accepting the underlying principle, by rejectingit, or simply by discussing it. A citator according to an embodiment ofthe invention may rely on the identification of Points of Law within anindexed opinion; a citator entry for a citing opinion can indicate thePoint or Points of Law within the indexed opinion that the citingopinion refers to. A user may then decide to examine only those citingopinions that refer to certain Points of Law. A citator according to anembodiment of the invention may additionally provide the Points of Law,e.g., as a list, that have been identified within a particular opinion.In addition to or instead of the foregoing, a citator may permit a userto restrict the citator display to only those citing opinions that referto a selected Point of Law.

FIG. 8 depicts a workflow for recording citator information according toan embodiment of the invention. As depicted, the workflow comprisesacquiring 340 the text of a judicial opinion, e.g., in electronic form.In block 342, the opinion is associated with direct history information,and in block 344, the opinion is examined as possible indirect history.

FIG. 9 depicts in greater detail the association of a newly-acquiredopinion with direct history according to an embodiment of the invention.In block 350, the opinion is retrieved from a queue of opinions thatawait analysis, which may comprise, e.g., retrieving the text of theopinion from a data store. The text of the opinion may be storedelectronically in association with metadata, and some or all suchmetadata may be retrieved and displayed in association with some or allof the text.

In block 352, the text is reviewed for any indication that this opinionis related to one or more other opinions. One such relationship mightexist, for example, when multiple opinions issue in the same case. Forexample, an opinion regarding a motion for summary judgment may refer tothe court's prior opinion denying a motion to dismiss the action.Similarly, the opinion of an appellate court may refer to the opinion ofthe court that made the appealed ruling.

Instead of or in addition to the foregoing, one case may involve thesame controversy as another, despite being part of a different formalproceeding. For example, different heirs under the same will may bringseparate actions to vindicate their own interests. Although neither caseis strictly considered part of the other's direct history, an analystaccording to an embodiment of the invention may record informationassociated with such controversies and may do so, e.g., as part ofidentifying relationships between opinions in the same case or by asimilar method that is done separately.

If the metadata displayed in block 350 appears in block 354 to includeinformation about all associated opinions, then the analyst may proceedto determine and record the type of decision in block 356. If not, theanalyst determines in block 358 whether the appropriate associations areapparent on the face of the opinion. If the associations are apparent,then the analyst records them in block 360. If not, the analyst forwardsthe opinion to a researcher for further inquiry in block 362.

In an embodiment of the invention, the analyst records the case type inblock 356. According to an embodiment of the invention, case types mayinclude, for example, attorney disciplinary actions, bankruptcies,criminal prosecutions, civil suits, and tax proceedings, among manyother possibilities. This recording may be conclusive or it may beprovisional and subject to further review as the opinion is processed.

In block 364, it is recorded whether the opinion is nothing more than anannouncement of a result, such as, e.g., “cert. denied” or “judgmentaffirmed.” Similarly, in block 366, it is recorded whether the opinionis an unsigned opinion of the entire court (referred to as a “percuriam” opinion), or is signed by one or more judges.

In block 368, the matter and result of the opinion are recorded innormalized form according to an embodiment of the invention. Here, the“matter” may refer to the question before the court, in response towhich the court issued the opinion, and the “result” may refer to thecourt's resolution of that question. Besides finding this information,however, block 368 may in an embodiment of the invention includerecording the information in standard terms.

For example, a court may write: “The judgments of dismissal arereversed, and the cases are to stand for further proceedings.” Accordingto an embodiment of the invention, this is recorded as: “Judgmentreversed, case remanded.” Such normalization may also include revisionof archaic terminology: “Plaintiff nonsuit” may, for example, become“case dismissed.”

In block 370, the effect of the ruling on any prior rulings in theaction are determined and recorded, e.g., affirming or reversing a lowercourt's decision.

According to an embodiment of the invention, an opinion is also reviewedfor its role in the indirect histories of one or more other opinions.Such review may, for example, comprise automatic identification of allcitations in the opinion followed by manual analysis of how the reviewedopinion treats the cited opinion. This treatment may be recorded, e.g.,in normalized terminology, as may be any textual indicators (or“signals”) that precede the cite and indicate, e.g., the relevanceand/or importance of the cited reference.

Normalized Points of Law

Choosing standard expressions of Points of Law has been discussed so farin connection with an example of one possible embodiment of a citator.But it will be appreciated that the selection of standard expressionsfor reference by a citator may, depending on the body of documentscovered by the citator, yield very many such expressions. Indeed,depending again on, e.g., the number, type, and scope of analyzeddocuments, the collected standard expressions may effectively describeone or more entire fields of law in one or more jurisdictions.

Thus, according to an embodiment of the invention, the substance of alegal principle is expressed in a standard form, e.g., a verbatim oredited version of an expression found in a judicial opinion. (Such astandard or normalized expression may be referred to herein as a “Pointof Law.”) Points of Law may, in an embodiment of the invention, becreated in the course of developing a citator, but they need not be. Anumber of Points of Law may be collected, e.g., in a database, and thelegal principles found in a plurality of legal opinions may beidentified and associated with the stored Points of Law.

According to an embodiment of the invention, collected Points of Law maybe organized within a hierarchy of topics and subtopics. For example, inconnection with an embodiment of the invention, a Legal Topic Hierarchyis provided that includes a classification of legal topics which may,e.g., span some or all fields of U.S. law. One example of a Legal TopicHierarchy includes a classification that includes about 120 broad fieldsof law (also referred to as “topics”), such as admiralty law, antitrustand trade, constitutional law, corporate law, and securities regulation.Each topic may then be divided into subtopics, each of which may containfurther subtopics, and so on. The extent of the outline that thehierarchy represents varies with, e.g., the particular body of knowledgethat is outlined and/or the expected use of the outline. For example,one exemplary Legal Topic Hierarchy may include more than 25,000 topicsand subtopics.

Treated as a graph, in which each topic and subtopic is considered anode, the hierarchy is not quite a tree, because some subtopics may befound in several places in the tree. For example, in a Legal TopicHierarchy, certain subtopics related to the Securities and ExchangeCommission might be placed under both administrative law and securitiesregulation. A structure of this kind is sometimes called a “polyarchy.”

In connection with such an embodiment, selection of a subtopic, e.g., asdiscussed below in connection with FIG. 15, may cause the display of thecollected expressions of Points of Law that have been associated withthat subtopics FIG. 10 depicts an example of such a display 400according to an embodiment of the invention. In an embodiment of theinvention, each of the Points of Law 405 is associated with, e.g., asubtopic within the topic hierarchy. The display 400, for example,indicates 407 that the displayed Points of Law 405 are associated withthe subtopic “Remedies” 409, which is a subtopic of “Violation of Stay”411, which is a subtopic of “Automatic Stay” 413, which is in turn asubtopic of the top-level topic “Federal Bankruptcy Law” 415.

As depicted in FIG. 10, the display 400 includes, as standardexpressions, the different conclusions that have been reached by courtsthat have addressed the subtopic of “Remedies” 409 for violations of theautomatic stay of pending actions that is imposed under federalbankruptcy law. So expressed, those conclusions are that “[a]ctionstaken in violation of the automatic stay provisions of the BankruptcyCode are void” 420 and, alternatively, that “[a]ctions taken inviolation of the automatic stay provisions of the Bankruptcy Code arevoidable” 422.

The information accompanying any Point of Law 405 may vary, depending,e.g., on the embodiment of the invention. As depicted in FIG. 10, forexample, each Point of Law states a legal principle 424 and an indexnumber 426 that may, e.g., uniquely identify the statement 424 withinthe synopsis. Below each Point of Law 405 and associated with it are oneor more references 428 to authorities that advance that point. Each suchreference 428 may include, e.g., a citation 430 to the opinion or otherauthority, which, for a judicial opinion, may include information suchas the title of the case 432, a reference 434 to a volume of a reporter436 and the page number 438 within that volume on which the indexedopinion begins, the court 440 that rendered the opinion, and/or the date442 of rendering the opinion.

For example, as depicted in FIG. 10, a reference 444 is made to thedecision of the U.S. Supreme Court in Kalb v. Feuerstein, which wasrendered in 1940, and which may be found within volume 308 of the UnitedStates Reports beginning on page 433. The reference includes so-called“parallel citations” 446 to additional reporters in which the opinionhas been published. In the depicted embodiment of the invention, thetitle 448 of the case is underlined, indicating that the title is ahyperlink to the indexed opinion. In an alternative embodiment of theinvention, one or more other portions of the reference 444 may behyperlinks instead of or in addition to the case title, and/or thehyperlinks may be indicated by other means in addition to or instead ofunderlining.

In the depicted embodiment of the invention, a reference may include,e.g., a summary and/or rephrasing 450 of the statement or action thatrelates to the Point of Law 405 associated with the reference 444. In anembodiment of the invention, the reference may include a portion of thetext of the authority in which the Point of Law is discussed. In thedepicted embodiment of the invention, it may be possible to select theinformation that appears with the reference. For example, the words“case extracts” 452 within the display 400 are a hyperlink that, whenselected, may lead, e.g., to a display 480 such as depicted in FIG. 11.In this display 480, a Point of Law 405 includes, e.g., one or morequotations 482 from the opinion, which may express, for example, a legalprinciple 484 significant to the decision and/or Point of Law 405 and/orthe holding 484 of the court on a question before it.

A synopsis of a body of knowledge, such as illustrated herein inconnection with the particular application to Points of Law, may also becombined with other features. For example, the citations gathered underone or more Points of Law may serve as the basis for an ecosystem searchas described below, instead of or in addition to one or more Law Notes.As another example, the synopsis can also be wholly or partiallycombined with one or more Law Notes, e.g., to provide editorialcommentary upon the collected legal principles.

Legal Topic Hierarchy

A topic hierarchy, such as may be used, e.g., to organize Points of Lawas discussed above, may be part of a framework for conceptuallyorganizing material related to a field of knowledge. A computer systemaccording to an embodiment of the invention may include a user interfacethat reflects such a hierarchy. Such an interface may then be used,e.g., to find and retrieve topical material.

FIG. 12 depicts a window 500 such as a computer system 140 (FIG. 2) maycause to appear on an output device 151 (FIG. 2), such as a computermonitor. The window 500 presents a hierarchical list 502 (or tree) oftop-level legal topics such as may exist within a Legal Topic Hierarchy.A user may view subtopics within a top-level topic by selecting thedesired top-level topic, e.g., via an input device 149 (FIG. 2).Depending on the configuration of the computer system, selecting a topicor other object may involve providing input, e.g., via a keyboard, touchscreen, and/or pointing device, such as a mouse or trackball.

A window 500 may include one or more buttons or other controls that,when selected, may make certain functions available to a user. Forexample, from the window 500 depicted in FIG. 12, selection of thebutton 504 labeled “Find Topic” leads to another screen (not pictured),in connection with which a user may enter one or more criteria to beused in searching the hierarchy. Selection of the button 506 labeled“Search Digest” may lead to another screen (not pictured) in connectionwith which a user may enter one or more criteria to be used in searchingsome or all of the information indexed according to the topic hierarchy.

FIG. 13 depicts a window 520 that presents an example of a hierarchicallist or tree of subtopics 522 directly beneath the topic “SecuritiesLaw” 524. This window 520 may appear, e.g., consequent to the user'sselection of the topic labeled “Securities Law” from the list 502 in thewindow 500 depicted in FIG. 12. Selection of the subtopic labeled“Broker-Dealer Regulation” 526, may in turn lead, e.g., to a window 540such as FIG. 145 depicts, in which a list or tree of second-levelsubtopics 542 appears under the selected first-level topic. As depicted,the presented window 540 includes a scroll bar control 544 to allow theuser to see and possibly interact with information that does not fit inthe provided space.

In connection with a display such as the one depicted in FIG. 14,selecting a topic or subtopic that contains further subtopics may causeone more level of subtopics to be displayed under the selected topic orsubtopics If the subtopics are already visible, then selecting on thetopic may cause all levels of subtopics below the selected topic orsubtopic to be hidden.

A topic or subtopic may be associated with one or more documents thatpreferably relate to that topic or subtopics FIG. 15 depicts a window560 including a portion 562 of a Legal Topic Hierarchy according to anembodiment of the invention. As depicted, some or all topics and/orsubtopics may be associated with at least one document called a “LawNote” 564, which relates to the associated topic or subtopics (Law Notesare discussed in more detail below in connection with FIGS. 19-21.)

Any particular topic or subtopic may, depending on the implementation,be associated with one or more documents. In an alternative embodimentof the invention, top-level topics may have no direct associations withany documents, but any subtopic may have documents associated with it,regardless of whether the subtopic itself has subtopics. In connectionwith an embodiment of the invention, every leaf node 566 of the topictree is associated with at least one Law Note 564.

For example, as depicted in FIG. 15, the subtopic “Net CapitalRequirements” 568 is associated with a Law Note 570 titled “Law FirmResearch on Net Capital Requirements.” “Net Capital Requirements” 568also includes two other subtopics, “Laws & Regulations” 572 and“Guidance and Interpretation” 574, which are both leaf nodes. “Laws &Regulations” 572 is associated with a Law Note titled “Quick Referenceto Net Capital Requirements Laws & Regulations” 576. “Guidance &Interpretation” 574 is associated with two Law Notes: one titled“Significant No-Action Letters on Net Capital Requirements” 578 and onetitled “Quick Reference to Net Capital Requirements Guidance andInterpretation” 580.

As an alternative to the depicted presentation, a topic or subtopic thatis associated with at least one Law Note or other document appears withsome indicia of the association when the documents themselves are notlisted. For example, an asterisk may appear next to a subtopic that hasa document associated with it, and selecting that subtopic may cause alist of associated documents to appear. Selecting a subtopic for which alist of associated documents is already displayed may cause that list tobe hidden.

Besides possibly being associated with one or more Law Notes, one ormore subtopics may also be associated with one or more other documents,e.g., news articles, statutes, or judicial opinions, that relate to thesubtopics Selecting a subtopic in such circumstances may cause a list ofassociated documents of one or more types to appear, and the list may ormay not include a Law Note.

Selecting a listed document, such as a Law Note, may cause some or allcontent of the selected document to be displayed. For example, thedisplay of the content of the document may replace some or all of thedisplay of the Legal Topic Hierarchy and/or appear in a new windowdisplayed on, e.g., a computer monitor. In connection with use of acomputer system that comprises and/or is coupled to more than onemonitor, the new window, which displays content from the selecteddocument, may, for example, appear on the same monitor as some or all ofthe Legal Topic Hierarchy, appear on a different monitor, and/or besplit between multiple monitors.

A system including an implementation of a Legal Topic Hierarchy mayfurther include a means for it to be customized. Such customization maydepend, e.g., on the individual user and/or on the basis of one or moregroups that the user is affiliated with. For example, a Legal TopicHierarchy displayed to an employee of a law firm may includefirm-specific material, such as briefs or memoranda. This customizationmay be done in one or more ways, depending on the embodiment of theinvention, including, e.g., by editing digital files stored on one ormore computers and/or through a drag-and-drop administrative interface(not pictured).

Any information, including standard and/or customized content, may bestored and provided, e.g., by a server provided by the user, a groupthat the user is affiliated with, a third party, or some or all ofthese. When multiple servers are used, some or all of the informationmay be duplicated on two or more servers. Depending upon theimplementation of the Legal Topic Hierarchy, a user may or may not beaware of any distinction between the presentation of standard contentand custom content.

As mentioned in connection with FIG. 12, a facility may exist by which auser may search for topics and subtopics that match entered searchcriteria. For example, selecting the “Find Topic” button 504 (FIG. 12)may cause the display of a window 600 such as the example depicted inFIG. 16. The user may dismiss the window 600 by selecting the buttonlabeled “Cancel” 602.

In connection with the window 600 of FIG. 12, the user can use the findtopic command by entering one or more search terms 604, such as“dealer,” in the provided text area 606. Selecting the button labeled“find” 608 causes the search to be executed against the Legal TopicHierarchy.

FIG. 17 depicts a window 620 such as may be displayed to present theresults of a topic search. As depicted, the search result includes alist of subtopics 622 that match the search term or terms. Also asdepicted, each responsive subtopic 622 is presented in terms of the fullpath through the Legal Topic Hierarchy from the top-level topic to theresponsive subtopic 622. For example, the response to a search for theterm “dealer” returns several subtopics, including “Broker-DealerDefined” 624. This is a subtopic of “Broker-Dealer Regulation” 626,which is itself a subtopic of “Securities Law.”

Subtopics 622 in the window 620 may be hyperlinks. Selecting such ahyperlink may cause, e.g., the display of a corresponding portion of theLegal Topic Hierarchy. FIG. 18 depicts such a display 640 that includesthe node corresponding to the selected path 624, the selected node'sparent 642, and the selected node's children 644, if any.

It may be possible to store and/or share topic searches and/or theirresults. As an implementation of such functionality, or in addition toit, a user may be able to encode the “find topic” command in a commandline or in hyperlink. Such an encoded command may be, e.g., sent as anelectronic message, allowing the sender to specify a search and/or aresult with relatively little opportunity for ambiguity and/or error.

Law Notes

As discussed above, a topic hierarchy may serve to organize information.For example, the Legal Topic Hierarchy may serve as a framework oroutline of legal knowledge. A subtopic within the Legal Topic Hierarchymay be associated with, e.g., a document such as a Law Note referred toabove.

In connection with an embodiment of the invention, the term “Law Note”may refer to a document that provides information relevant to one ormore matters of law, corresponding to one or more topics and/orsubtopics in the Legal Topic Hierarchy. A Law Note may, for example, beprepared by one or more human authors and/or editors. The length of anyLaw Note may vary depending on, e.g., the subject matter, the type ofLaw Note (as discussed below), and the depth of coverage.

The content and types of Law Notes associated with the Legal TopicHierarchy may vary. One exemplary implementation in connection with anembodiment of the invention includes at least three specific kinds ofLaw Note. The first kind, which may be called a “discussion note,” mayresemble a case law annotation or a section of a legal treatise in thatit reviews and analyzes a specific legal topic. The discussion commonlycites authorities-including, for example, judicial decisions, statutes,and regulatory rulings-that are relevant to the topic, analyzing some indetail and preferably citing others, e.g., from as many others aspossible while keeping within reasonable limits both the length of theLaw Note and the amount of effort required to prepare it. Under eachlegal point, citations are broken down by jurisdiction.

FIG. 19 depicts a window 660 within which a discussion note 662 may bepresented in accordance with an embodiment of the invention. Asdepicted, titles 664 of authorities (e.g., judicial opinions) and/orcitations to them may be hyperlinks. When selected, such a hyperlink maylead, e.g., to the cited authority and/or further information related toit. The existence of a hyperlink may be indicated, e.g., by highlightingand/or underlining.

The second kind of Law Note included in the exemplary implementation isdisplayed within the window 670 depicted in FIG. 20. The Law Note, whichmay be referred to a “law list,” comprises references 672 to authoritiesthat are relevant to the topic of the note. As with a discussion note,references may be hyperlinked citations that lead to the respectivecited authorities.

The third kind of Law Note included in the exemplary implementation isdisplayed within the window 680 depicted in FIG. 21. The depicted LawNote, which may be referred to as a “directory,” comprises a classifiedlist of further references relevant to the topic of the note. As withthe other kinds of Law Notes, some or all listed references areaccompanied by a description of the reference, its relevance or both.

For example, as depicted in FIG. 21, the window 680 displays a portionof a directory note 682. As depicted, the directory note 682 does notfit in the viewing area of the window 680, and a scroll bar 684 isprovided, enabling the user to select which portion of the directorynote 682 will be displayed. The depicted directory note 682 comprisesheadings 686, under which references 688 to documents are collected. Forexample, as depicted, Regulation AC 690 and Regulation BTR 692 of theU.S. Securities and Exchange Commission (“SEC”) appear under thedescriptive heading “SEC Regulations” 694. The next heading, “SECAdopting Releases” 696, collects references to documents that expressthe adoption by the SEC of changes to rules that relate to the subjectmatter of the directory note 682. For example, FIG. 21 depicts areference 698 to a rulemaking related to the National Association ofSecurities Dealers, the New York Stock Exchange, and governance ofcorporations whose shares trade in those markets.

As depicted in FIG. 21, a reference 688 to a document in a directorynote 376825 may include, e.g., a title and/or description of thedocument 690 and a citation 692 that may be used to identify thedocument. Preferably, a citation 692 is also a hyperlink to the citeddocument or other resource and is displayed, e.g., highlighted and/orunderlined, to indicate that it is a hyperlink. A reference may includeand/or be associated with other information in addition to and/orinstead of some or all of the information depicted in FIG. 21, and,depending on the implementation, this other information may comprise ahyperlink to some resource.

Ecosystem Search

Interrelationships between documents in a collection of documents may beused to define a subset of the collection, within which a user maysearch for and/or within documents. Because the subset is defined by theinterrelationships between the documents, the subset is sometimes calledan “ecosystem.” In one implementation, the interrelationships arecitations from one document to another; it may be inferred that if onedocument cites another, then the two documents may refer to at least onecommon topic.

Searching with a collection defined at least in part by citationsbetween and among documents in the collection is discussed in detail inthe related, commonly-owned, pending U.S. patent application Ser. No.11/412,315, filed Apr. 26, 2006, and titled “System and Method forTopical Document Searching,” which has been incorporated herein byreference.

In this context, an ecosystem includes the idea of an ecosystem “level,”which relates to the expansiveness of the definition of the ecosystem. Alevel 0 search may, for example, look for specified keywords only in thetext of one or more specified documents or parts of documents. But thesource documents may cite other documents, and it may be inferred thatthe cited documents are themselves likely to be relevant to the sametopics as the source documents. Thus, continuing the previous example, alevel 1 search may look for keywords in the text of the source documentsand in the text of each document that any of the source documents cites.The set of searched documents may be expanded iteratively in the sameway.

The idea of an ecosystem level permits a precise definition ofsearchable ecosystems using the language of mathematical induction. Leta level 0 ecosystem be defined to be the set of one or more documents(or parts of documents) within a larger collection of documents, some orall of which cite other documents in the collection. Then, given thelevel N ecosystem, where N is a non-negative integer, the level (N+1)ecosystem is defined as the union of the set of documents in the level Necosystem and the set of all documents in the collection that are citedby any document in the level N ecosystem.

Depending on the collection of documents, there may be one or moreecosystems such that the level N ecosystem is identical to the level(N+1) ecosystem for all N above a certain limit. In other words, once acertain level is reached, every document that is cited within theecosystem is itself already contained in the ecosystem. In such a case,the level N ecosystem may be said to be exhaustive.

In some circumstances, e.g., when applied to certain fields of knowledgeand/or certain collections of documents, increasing the level of theecosystem beyond a certain point may decrease the topical focus of theecosystem. In such circumstances, long chains of citations may dilutethe relevance of newly-added documents to the original document. In onepreferred implementation, for example, which uses Law Notes as the basisfor defining a searchable ecosystem within a database of legalmaterials, a user may choose to search within ecosystems of levels 0, 1,or 3.

Once an ecosystem has been defined, a search (such as a keyword search)within the ecosystem will return the document or documents within theecosystem that satisfy the search criteria.

I claim:
 1. A method of displaying an entry in a citation index for acited document cited in at least one citing document, the entrycorresponding to at least one citation in the at least one citingdocument that comprises text, the at least one citation identifying thecited document and being introduced in the text of the at least oneciting document by a signal, the method comprising: retrieving from acomputer-readable storage medium first information that identifies theat least one citing document and second information that identifies thesignal in the at least one citing document that introduced the citationto the cited document; and causing an electronic display device todisplay the entry, the entry being based on the first information andthe second information and comprising identification of the citingdocument and identification of the signal.
 2. The method of claim 1,wherein the entry comprises the signal.
 3. A system for displaying anentry in a citation index for a cited document cited in at least oneciting document, the entry corresponding to at least one citation in theat least one citing document that comprises text, at least one of thecitations identifying the cited document and being introduced in thetext of the at least one citing document by a signal, the systemcomprising: a programmable processor, a memory coupled to the processor,a computer-readable storage medium, and an electronic display device;the memory storing instructions that, when executed by the processor,cause the system to carry out a method that comprises retrieving fromthe computer-readable storage medium first information that identifiesthe at least one citing document and second information that identifiesthe signal in the at least one citing document that introduced thecitation to the cited document; and causing an electronic display deviceto display the entry, the entry being based on the first information andthe second information and comprising identification of the at least oneciting document and identification of the signal.
 4. The system of claim3, wherein the entry comprises the signal.
 5. The method of claim 1,comprising retrieving from the computer-readable storage medium anexcerpt in the at least one citing document which includes a citation ofthe cited document and displaying the excerpt in association with thedisplayed identification of the at least one citing document.
 6. Thesystem of claim 3, wherein the method carried out by the at least oneprocessor comprises comprising retrieving from the computer-readablestorage medium an excerpt in the at least one citing document whichincludes a citation of the cited document and displaying the excerpt inassociation with the displayed identification of the at least one citingdocument.